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5

IRPLDIM2U

BALLAST DESIGN

The ballast design incorporates two parts, hardware and software. The ballast controller design portion incorpo-

rates most of the hardware design. The digital design control portion incorporates most of the software design.

Appendix A shows the complete schematic and Appendix B the Bill of Materials.

The Ballast Controller Design

The design of the Ballast control portion of the circuit has been accomplished in International Rectifier’s Reference

Design IRPLDIM1. Refer to this for waveforms and specific calculations regarding the ballast controller portion of

this design.

Signals of the IR2159

The communication between the microcontroller and the IR21592 is done with four signals, as shown in Fig. 4.

These signals are used for digital dimming (RB3), turning the ballast on or off (RB4), and fault detection (RB5 &

RB6). The microcontroller controls the IR21592 by the following 3 pins: pin SD for shutdown of the IC (active high),

pin FMIN used for fault detection (0 if the IC is

in fault mode) and pin DIM to control the bright-

ness. The microcontroller receives lamp infor-

mation by the signal Lamp-out, connected to

the lamp.

1

2

3

4

5

6

7

8

18

17

16

15

14

13

12

11

RA2

RA3

RA4

RA5

VSS

RB0

RB1

RB2

RB7

VDD

RA6

RA7

RA0

RA1

RB5

RB6

9

10

RB3

RB4

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

VDC

VCO

CPH

DIM

MAX

MIN

FMIN

IPH

LO

COM

VCC

VB

VS

HO

SD

CS

R25

C17

RDIM

1.25V

2.5V

3.75V

If 0 IC OFF

If 1 IC OK

TURN ON IC

TURN OFF IC

C11

R16

R17

VDD

VSS

Lamp

Out

If 0 Lamp OK

If 1 Lamp Fault

Interfac

e

with

Optos

TR data signal

from the network

to the micro

RX data signal

from the micro

to the network

Fig. 4 Micro/IR21592 Communication